This invention relates to the active acoustic silencing of conversations being conducted by communications equipment such as telephones, transmitting radios and other electronic apparatus.
Remote communication between people operating telephones, radios or other devices is common place to the point where conversations often take place while either or both operators"" speech is unintentionally overheard by other people. Examples include cellular telephones used in public, telephones used in multi-occupant rooms such as office cubicle spaces, open sided public pay phones, 2-way radio transmissions, and anywhere the operator of a communications device can be overheard. The result is that the operator can not have a private conversation. In addition to the operator""s loss of privacy, people overhearing intelligible conversation are significantly distracted resulting in loss of concentration and efficiency.
Prior art is from two areas: communications operators"" privacy and active acoustic silencing.
Privacy for the operators speaking on communications devices has previously only used passive devices such as U.S. Pat. No. 5,182,883 to Amberson a telephone enclosure or the xe2x80x9cHush-a-Phonexe2x80x9d type handsets that enclosed the operator""s mouth such as U.S. Pat. No. 271,903 to Nichols. These devices use passive acoustical dampening to quiet the sound or sealed off the operator""s voice to prevent it from propagating. The sealing devices either required putting a sealed container around the operator (e.g. telephone booths with closing doors) or for the device to seal to the operator, i.e. around the operator""s mouth, with a host of maintenance and sanitary issues that many patents tried to addressed. Both types are rarely used any longer.
There is a notable lack of devices applying active acoustic silencing or active acoustic canceling (synonymous terms) to communications operator privacy. Active acoustic silencing was first patented in the Lueg U.S. Pat. No. 2,043,416. Active acoustic silencing has seen application in reducing noise in confined spaces like ducts and exhausts, as in U.S. Pat. No. 4,815,139 to Eriksson, et al. and in reducing background noise for operators listening to acoustic signals on headsets, as in U.S. Pat. No. 5,675,658 to Brittian. Methods and devices for applying it to specific noise sources have been patented several times such as U.S. Pat. No. 5,872,853 to Marquiss for reduce noise from highways and U.S. Pat. No. 5,889,869 to Botros et al. for reduce noise from adjacent workspaces.
Efforts up to now to provide such conversational privacy involve passive mechanical arrangements which have several problems including: inconvenient to use, unsanitary, high maintenance, and size.
The need for privacy for telecommunication operators has increased with cellular telephones and office cubicle telephones providing no privacy for the operator and causing a significant distraction for other people in the area.
This invention utilizes active acoustic silencing to provide speech privacy for the operator of communications equipment such as all types of telephones, transmitting radios, intercoms, and the like. The invention also reduces distracting noise from the operator""s speech for the people in the adjacent area. The invention attaches to or integrates with the communications equipment with no impact on the equipment""s convenience or sanitation, and little impact on maintenance or size greatly improving on prior efforts to obtain such privacy.
The invention applies active acoustic silencing to the problem of speech privacy for the operator of communications equipment. The active acoustic silencing of the operator""s voice while using communications equipment results in both privacy of the operator""s communications and reduction in distraction for other people in the vicinity.
The invention may be embodied as an attachment to existing communication equipment, with or without electrical connections, or embodied as an integral part of a communications device.
The preferred embodiments of the invention add one or more loudspeakers behind the microphone of a communication device""s handset or headset, and some additional circuitry inside the communication device. Other embodiments of the invention vary in their degree of integration with the communications device. A second embodiment of the invention replaces the communications device""s handset or headset apparatus and connects electrically to the communications device. Another embodiment physically attaches to the communications device with no electrical connections and uses a separate microphone, placed adjacent to the communications device microphone.
The generalize function of the invention is illustrated in FIG. 1 and summarized as follows. A unidirectional microphone (1) captures the operator""s speech (4) just in front of the operator""s mouth (10). The electrical signal from the microphone goes to a electrical or electronic circuit (6) which processes the signal to: amplified it, split off the signal to be sent by communication equipment, modify the signal to produce the silencing signal, amplify the signal to the needed volume for the cancellation, and send the signal to the loudspeaker (2) placed in front of the operator""s mouth and further away than the microphone (1).
In FIG. 1, the acoustic silencing takes place in the air between the element of the microphone (1) and the loudspeaker (2). The operator""s speech modulates the sound pressure level verses position (7) commonly called sound waves. The silencing loudspeaker (2) produces the mirror sound pressure level (9). Where the two sound waves meet (8) the both sounds are reduced by active acoustic cancellation.
Applications of the invention include embodiments for all types of communications devices including: cellar telephones, cordless telephones, wired telephones, intercoms or 2-way radios. The invention is applicable any where a communications device operator""s speech may be overheard to preserve privacy or to avoid disturbing others.